This invention relates to a novel composition comprising an epoxy resin and a bitumen material.
Of the bitumen materials, tar is well miscible with an epoxy resin, especially glycidylether of bis-phenol, and mixtures thereof have long been used as anti-corrosion paints and paving materials. The mixtures are cured with a hardener and form films having excellent characteristics including excellent adhesion to steel and ballast. However, they have some defects. For one thing, benzopyrenes contained in the tar is a source of environmental pollution, and for another, the formed coating films become brittle with the passage of time.
As bitumen materials which can be substituted for the tar, there are asphalt materials and lubricating oil materials of similar compositions. But they do not have good compatibility with epoxy resins, especially bis-phenol glycidylether type resin. So it is generally difficult to prepare a homogeneous mixture of an asphalt or a lubricating oil and said resin.
Therefore, various techniques have been attempted including methods in which specific hardeners are used; methods in which tar and asphalt are used in combination, and methods in which a large amount of a co-solubilizer is used, as disclosed in Japanese patent application Publications No. 8468/63, 8035/69, 21115/71, 1840/73, etc. But all of these methods still have the following defects: (1) Selection of hardeners from a wide range, which is possible with the epoxy resins, is not permitted; (2) Plasticity of the composition is disadvantageously increased by the use of a large amount of co-solubilizers; (3) Properties of the resulting cured products such as hardness, thermal deformation resistance, etc. are deteriorated; etc. Also these methods lack versatility and adaptability to all kinds of asphalts of different compositions from different countries. For instance, if an asphalt from Iranian crude oil, which is rich in aromatic ingredients, is replaced with the asphalt from an Arabian, Venezuelan or USSR crude oil, which is lower in aromatic contents, sufficient compatibility between the epoxy resin and the asphalt can no longer be achieved with the conventional co-solubilizer, nonylphenol for instance, and thus the epoxy esin and the asphalt in the mixture are readily separated.
Our aim was to eliminate these defects of the known epoxy resin-bitumen material compositions, and we have found a new co-solubilizer suitable for this purpose.